It's a call to action, and the target is clearly the Muslim Brotherhood. Its leaders say the call is a threat, and are refusing to budge in their demand for President Morsi's reinstatement.

But Gen Sisi's call has been backed by Tamarod, the rebel movement that co-ordinated the protests in June which brought millions onto the street and resulted in President Morsi's removal. They say it's the army and the people against terrorism - but this is clearly the army and some of the people against the Muslim Brotherhood.

Over 100 people have already died in fighting, mostly in Cairo, since the crisis began. Perhaps it shows the military's anger over last night's bombing of a police station in the city of Mansoura, which left one soldier dead, and a dozen policemen injured. Or it may reflect their frustration at President Morsi's supporters' refusal to disappear.

This latest intervention by the military makes it more difficult for them to deny the plain fact of who is running Egypt. It doesn't appear to be the interim President Adly Mansour - it is the man whose portrait is plastered on walls and kiosks around Cairo: Gen Abdel Fattah al-Sisi.

"He is proving that he is the actual ruler of the country, and that the president, his vice president and the government do not hold any power," he added.

Army 'united'

In a speech at a military graduation ceremony, which was broadcast on television, Gen Sisi said: "I urge the people to take to the streets this coming Friday to prove their will and give me, the army and police, a mandate to confront possible violence and terrorism."

"So that in case there was a resort to violence and terrorism, the army would have a mandate to confront this."

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Our correspondent says that Gen Sisi's call showed who was really in charge in Egypt - not the interim president picked by the military, Adly Mahmud Mansour, but the military itself.

He says it may be a sign of frustration that protests against the interim government are still going on.

It also followed an overnight bomb attack on a police station in Mansoura, 110 km (68 miles) north of Cairo, that killed one person and wounded two dozen others.

A government spokesman condemned it as a terrorist attack.

In Cairo, two people were reported to have been killed in clashes at a pro-Morsi demonstration overnight. That followed nine deaths in the city on Tuesday.

Gen Sisi, who is also the defence minister in the new government, rejected rumours about divisions within the army ranks. "I swear by God that the Egyptian army is united," he said.

Referring to the army's intervention to remove Mr Morsi early this month, Gen Sisi said: "I urged the former president to be a president for all Egyptians".

And, recalling the 2012 presidential election when Mr Morsi was voted into office, he said that he had advised Islamists not to field a presidential candidate - but that they had ignored him.